The present invention relates to a vein valve cutter for use in disrupting vein valves during vascular reconstructive surgery. In its more particular aspects, it is concerned with a method and apparatus for use in a procedure known as in-situ saphenous vein bypass.
In the in-situ saphenous procedure, atherosclerotic occlusive disease in the femoropopliteal arterial system is bypassed with a segment of nearby saphenous vein left "in situ"; that is, undissected from its native bed. In order to use the saphenous vein as an arterial conduit, the valves of the vein must be disrupted. This allows arterial flow to proceed in a direction normally prevented by the intact valves. The saphenous vein segment, now devoid of valves, is anastamosed to the femoral artery and a distal artery, such as the tibial artery, to bypass the diseased section.
Previous efforts to achieve the in-situ disruption of the valves within a vein have included the following techniques:
1. Valve incision with a pair of tiny scissors performed through venotomies proximal the valve sites, or through side branches close to the valve sites.
2. Valve incision performed from below the valve site by passage of a valvulotome through the valve followed by incision of the leaflets upon pulling of the device back through the valve. The valvulotome is a long thin instrument with a curved hook-like cutting tip. It may be introduced in the vein being treated through a side branch.
3. Vein strippers which break the valves upon passage of the strippers in a direction against normal blood flow. Such strippers consist of one or two bullet-shaped members which are initially introduced in either antegrade or retrograde directions. One type of stripper, known as a "Cartier stripper" employs a cone-shaped stripper with a circular cutting edge around its divergent end. This type of stripper is passed through the valve apex end first in the normal direction of blood flow and then drawn back in the reverse direction to cut the valve with the circular cutting edge.
4. A more recent type of stripper somewhat related to the latter type provides a double cylinder arrangement which is passsed through the vein. The initial cylinder is blunt and the second cylinder has two cutting blades. In use, the instrument is first passed through the vein and valve to be treated in the direction of normal blood flow and then drawn back in reverse direction to draw the cutting blades of the second cylinder through the valve.
The above prior techniques involve either cutting of the valves through an open incision near the valve site, or the blind passage of a cutting or stripping device. The direct open incision method of valve cutting is tedious and time-consuming. Blind incision of valves, however, is hazardous to the vein being treated. Side branches may be caught and avulsed by the valve cutters. Endothelial damage may also result from the blind incision of valves.